1. Field of the Invention
The invention relates to the addition of beer fermentation products to brewer's wort. In particular, the invention relates to the use of ultrafiltration and, especially, to the use of dialysis in modifying a beer wort's constituent profile prior to the fermentation thereof.
2. Description of Related Art
The process of preparing fermented malt beverages, such as, beer, ale, porter, malt liquor, and other similar fermented alcoholic beverages, hereinafter referred to simply as "beer" for convenience, is historically well established. As practiced in modern breweries, the process, in brief, comprises preparing a "mash" of malt, usually with cereal adjuncts, and heating the mash to solubilize the proteins and convert the starch into sugar and dextrins. The insoluble grains are removed by filtering and then washed with hot water that is then combined with the soluble material. The resulting wort is boiled in a brew kettle to inactivate enzymes, sterilize the wort, extract desired hop components from added hops, and coagulate certain protein-like substances. The wort is then strained to remove spent hops and coagulum, cooled, pitched with yeast, and fermented. The fermented brew, known as "green" or "ruh" beer, is then aged or "lagered" and clarified, filtered, and carbonated to produce the desired beer. In a widely practiced high gravity brewing procedure, beer is brewed at a slightly elevated alcohol content of approximately seven percent to eight percent vol/vol alcohol content. This brew is then diluted to the desired value of alcohol or, for example, five percent vol/vol.
The use of semi-permeable membrane technologies in the production of brewery beverages is known in the art. Generally, such use is confined to the production of low alcohol beverages, as exemplified in a variety of issued patents.
U.S. Pat. No. 4,499,117 relates to a method consisting of subjecting a natural alcoholic liquid to three successive steps of non-denaturing physical fractionation. The first step is a molecular ultrafiltration that is performed under low pressure though a semipermeable ultrafilter, having a splitting threshold of between 30,000 and 1,000 and preferably around 10,000. The second step is a reverse osmosis step applied to the ultrafiltrate that is produced during the first step. In the second step, the ultrafiltrate is passed through a semipermeable membrane, the splitting threshold of which is between 500 and 100 and, preferably, about 250. The third step consists of evaporating and distilling under vacuum, at low temperature, the ultrafiltrate resulting from the second step. Natural beverages having a low alcohol content are thus obtained.
U.S. Pat. No. 4,532,140 discloses a method in which an alcoholic liquid obtained by fermenting a must or a wort is initially subjected to ultrafiltration or to reverse osmosis. This process obtains a permeate and a concentrate. The permeate contains a higher proportion of water and alcohol than the starting liquid. The concentrate contains a higher proportion of the substances that flavor the starting liquid. The permeate is then subjected to reverse osmosis using a membrane that is substantially impermeable to alcohol, while still being permeable to water. The concentrate from the second step is added to the concentrate from the first step to produce a liquid that has a higher concentration of alcohol than the starting liquid. The resulting liquid can be useable at the higher concentration as a beverage. Alternatively, the liquid can be used for transport and/or for storage with water being added to the liquid to restore the beverage substantially to its starting condition before being consumed.
U.S. Pat. No. 4,581,236 pertains to fermented beverages having reduced alcohol content. These beverages are made by causing the fermented beverage having a normal alcohol content, which is produced in the fermentation, to flow along one face of a dialysis membrane at a pressure differential below 5.0 bar. Simultaneously, a dialysate liquid that is substantially alcohol-free is passed along the other face of the dialysate membrane. An apparatus for performing the process comprises a housing in which two separate chambers are provided. Each chamber has separate inlet and outlet ducts. The inlet ducts are connected to separate feeding devices for liquids. Separate regulation devices are arranged for regulating the flow through each of the two chambers and means are provided for regulating the pressure differential between the two chambers.
U.S. Pat. No. 4,664,918 discloses a dialysis process wherein a fermented beverage is obtained The fermented beverage is conducted along one side of a dialysis membrane with a suitable dialysate fluid containing extract substances, such as alcohol-free fruit beverage and a fermented beverage from which the alcohol has been removed, flowing on the other side. This process simultaneously yields two finished drinks of low alcohol content. To improve the alcohol-reduced beverage, the extract-containing fluid is, in certain instances, conducted in circulation, and the alcohol is removed from the dialysate by vacuum distillation.
U.S. Pat. No. 4,681,767 describes a method for decreasing the alcohol content of alcohol-containing beverages, particularly wine or sparkling wine. This method uses a reverse osmosis process, in which extract substances are added to the dealcoholized beverage. In order to avoid the addition of foreign water to the beverage, the alcohol-containing permeate, which is obtained by reverse osmosis from the beverage subjected to dealcoholization, is distilled in a vacuum. The permeate water produced therefrom is re-fed to the beverage that has been subjected to the dealcoholization. The amount of permeate distillate removed from the beverage, which essentially consists of alcohol, is fed to the beverage, which has also been obtained by vacuum distillation from an additional beverage. In this manner, particularly high quality sparkling wine can be produced.
U.S. Pat. No. 4,816,407 discloses the production of low-ethanol wines and other alcoholic beverages by treating ordinary alcoholic beverages with membrane extraction methods. Semipermeable membranes and extraction fluids comprising either a nontoxic, water-immiscible organic solvent or an aqueous, membrane-impermeable solution with low-molecular weight are used under mild conditions to extract ethanol selectively from alcoholic beverages substantially intact. A complement of other organic constituents that contribute to the color, aroma, and taste of the beverage are left substantially intact. The method can be adapted to continuous processing of alcohol-containing beverages, in which an ethanol-rich product is continuously recovered from the organic or aqueous extraction fluid and the latter is continuously regenerated and subsequently recycled to the membrane extraction unit.
U.S. Pat. No. 4,933,198 relates to the production of low-ethanol wines, beer, distilled spirits, and other alcoholic beverages by treating ordinary alcoholic beverages with membrane extraction methods. Semipermeable membranes and gas-phase extraction fluids are employed to extract ethanol selectively into the gas-phase, while leaving substantially intact the complement of other organic constituents that contribute to the color, aroma, and taste of the beverage. Methods are provided for balancing the water activity of the gas-phase extraction fluid to be about equal to that in the beverage, so as to inhibit water transport across the membrane independent of the ethanol/water selectivity of the membrane.
U.S. Pat. No. 4,943,436 relates to beer production and intermediate products for use therein. In particular, the patent discloses a process for the production of a beer wherein, prior to fermentation, the wort is subjected to a separating technique. The separating technique produces one product, which is lower in fermentable low molecular weight components of the wort, in substantially the same concentration as the feedstock. Subsequently, the separated product is fermented to produce a beer.
U.S. Pat. No. 4,988,525 discloses a process for the selective removal of volatile substances from liquids, in which the initial liquid is fed to a crosscurrent diaphragm separation device. The permeate, consisting of water and volatile substances, is separated in this device by increased transdiaphragm pressure and concentration difference. The permeate is then fed into a further liquid-volatile separation device, in which the alcohol is removed by distillation. The permeate, now consisting only of water, salts, acids, and extracts, is fed back into the crosscurrent diaphragm separation device, where it flows through the permeate side countercurrent to the flow of the retentate.
U.S. Pat. No. 5,075,123 discloses a process and apparatus for removing alcohol from beverages. This process includes removing alcohol from the beverage to a dialysate by dialysis in a dialysis chamber. The alcohol is then removed from the dialysate by vacuum in a vacuum stripping column, wherein the dialysate is cooled in a heat exchanger and thereafter in a cooling device prior to entry of the dialysate into the dialysis chamber. The dialysate is heated in the heat exchanger and thereafter in a heater prior to removal of the alcohol from the dialysate by vacuum.
U.S. Pat. No. 5,143,526 discloses a method and an apparatus having applicability to the manipulation of the concentration, by partial depletion or enrichment, of one or more volatile components. The manipulation of the concentration of volatile components in a given liquid is performed while leaving the other volatile components in the liquid in a substantially undisturbed or unadulterated state.
There remains a need in the industry, however, for a process whereby the brewer can control the constituent fermentation product profile in the final, post-fermentation product according to predetermined criteria so that particular market tastes, for example, flavor, alcohol content, aroma, appearance, and the like, can be addressed and controlled in an efficacious manner heretofore unavailable in the art.